Fast response liquid crystal mode

ABSTRACT

A novel nematic liquid crystal (LC) mode is based on the Fringing-Field-Switching of Vertically-Aligned liquid crystals. The VA-FFS mode is capable of generating very fast optical modulation without the use of very thin cell gap. IA major feature of this LC mode is that it has unusual fast relaxation time compared with the conventional nematic LC modes that require a thin cell gap. This fast relaxation occurs even at very low applied voltages and the operation is very stable. The fast-response mechanism of this LC mode involves the confinement of liquid crystal molecular switching within self-imposed thin LC layers. The present invention provides a novel approach to overcome the fundamental problem of the long relaxation time of the conventional nematic liquid crystal modes.

This invention claims the priority of U.S. Provisional Application Ser.No. 60/480,622 filed Jun. 23, 2003 and was supported in part byDepartment of Defense Advanced Research Project Agency (DARPA) andRaytheon Electronic Systems under Contract No. 65-04-878.

FIELD OF THE INVENTION

This invention relates to a liquid crystal operation mode, and inparticular to methods and apparatus for producing a stable andfast-response optical modulator for use in optical communications andadvanced display systems.

BACKGROUND AND PRIOR ART

Due to the slow response of nematic liquid crystals (typically 25milliseconds (ms) to 100 ms), applications for nematic liquid crystalstoday have been mainly limited to those with relatively low data rates.This shortcoming is caused by the fact that the switching speed ofnematic liquid crystals is often limited by its long relaxation time.Unlike the switching-on process, which is electric-field driven, therelaxation process (i.e. switching-off) is not electric-field driven andis generally a much slower process. This relaxation process is slower ina thicker cell since the restoring force provided by the alignmentlayers (substrate surfaces) to the bulk is weaker in a thick cell. Inorder for liquid crystal devices to switch at high speed, i.e. withshort relaxation time, one often needs to use very thin cell gap (e.g.<2 μm) such that the restoring force provided by the alignment layersremains very high in the bulk of the liquid crystal. This thin cell gaphowever increases fabrication difficulty, especially when the panel sizeis large, and also limits the potential optical retardation since cellgap is limited. It is therefore anticipated that if a nematic liquidcrystal mode capable of achieving very fast response (e.g. <5 ms)without the use of thin cell gap can be realized, it can greatly advancethe development of high-speed applications in various areas such asthose in optical communication systems (e.g., optical phase modulators)and advanced display systems, e.g., color sequential displays andtelevision (TV) displays. Although a liquid crystal mode, known asPi-cell Bend mode or Optically Compensated Bend (OCB) mode, capable ofgenerating very fast response without the use of thin cell gap has beenreported, this liquid crystal mode is unstable and requires a constantbias voltage.

With regard to Fringing-Field-Switching mode (FFS), the electrode designin the present invention is very similar to the FFS mode, as shown inFIG. 6, which was proposed by researchers in Korea for obtaining highefficiency wide-viewing-angle liquid crystal displays. The FFS modedeveloped in Korea has Parallel-Alignment (PA) at the off-state whichleads to much slower response since the LC molecules in the whole bulklayer also switch without the restriction of the boundary effects, andthe restoring force is mainly governed by the elastic constant K₂₂ whichis small. See “Fringing-Field-Switching mode (FFS)”, Seung Hong et al,Japanese Journal of Applied Physics, Vol. 39, p. L527, 2000.

Vertical-Alignment-In-Plane-Switching (VA-IPS) is discussed by W. Liu etal, in SID Digest '98, p. 319, 1998. Researchers proposed the VA-IPSmode which combined VA alignment with IPS electrode design. The VA-IPSmode can achieve a wide-viewing angle property but the response time isnot very fast. A major difference between VA-IPS and the presentinvention is that the gap l between the positive and negative electrodeis much larger in VA-IPS mode as shown in FIG. 7 whereas l is almostzero in the present invention (separated by a passivation layer only).Therefore the electric field in the VA-IPS mode is much more spread outand less localized which results in large switching of LC bulk layer andhence small boundary effect and slower response time.

Another liquid crystal mode of interest is the Optically CompensatedBend mode (OCB) discussed in Japanese Journal of Applied Physics, Vol.39, Part 1, No. 11, H. Nakamura et al, p. 6368-6375, (2000). OCB is aliquid crystal mode that can generate very fast response without the useof very thin cell gap or special driving conditions. At off-state, thismode has Parallel Alignment (PA) with opposite top and bottom pre-tiltsas shown in FIG. 8. Under a certain bias voltage, the molecules in thebulk are switched to vertical. Modulation of electric field above thisbias voltage causes switching of the molecules near the boundaries. TheOCB liquid crystal mode has very thin active LC layers and very strongboundary effects due to K₃₃ and K₁₁ as shown in FIG. 8. The OCB mode ishowever rather unstable since it involves the Splay to Bend transitionand it also requires a constant bias voltage.

The following patent references are related to the use of liquid crystaldisplay devices, but have no mention to Fringing Field Switching modefor Vertically Aligned liquid crystals.

U.S. Pat. No. 5,128,786 to Yanagisawa describes a LC display devicewherein the image elements are arranged like a matrix with discontinuouselectrodes. U.S. Pat. No. 5,179,460 to Hinata et al. discloses an inputstructure for a LC display that prevents electrode peeling andeliminates bending stresses and cracks in the electrode. U.S. Pat. No.5,377,027 to Jelley describes a light-emitting LC display wherein amatrix area separates pixels. U.S. Pat. No. 5,781,259 to Shinomiya etal. describes another LC display device with transparent substrates,transparent pixels and transparent electrodes, the transparent pixelsare separated from polymer portions with a shielding layer of metalfoil. U.S. Pat. No. 6,031,593 to Morikawa et al. describes a spacinglayer for LC display using light shielding layer. Pixels are formed withflattened film in between to suppress disinclination. None of thereferences suggest a configuration that uses self-imposed boundarylayers by vertically aligned liquid crystals. Commercial demand is verystrong for fast response, stable and easily fabricated liquid crystaldevices.

The present invention provides a novel liquid crystal mode capable ofproducing very fast response, due to fast relaxation time, without theuse of thin cell gap is disclosed. This invention is very stable and hasvery short relaxation time even at low voltages.

SUMMARY OF THE INVENTION

The first objective of the present invention is to provide afast-response liquid crystal modulator.

The second objective of the present invention is to provide afast-response liquid crystal modulator based on the use ofFringing-Field-Switching (FFS) to the Vertical Aligned (VA) liquidcrystals (denoted by VA-FFS).

The third objective of the present invention is to provide afast-response liquid crystal modulator without the use of thin cell gap.

The fourth objective of the present invention is to provide afast-response liquid crystal modulator with self-imposed strong boundarylayers such that very fast relaxation occurs even in a thick cell.

The fifth objective of the present invention is to provide afast-response liquid crystal modulator with high stability.

The sixth objective of the present invention is to provide afast-response liquid crystal modulator even at low operating voltage.

Further objects and advantages of this invention will be apparent formthe following detailed description of a presently preferred embodiment,which is illustrated, schematically in the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the structure of the liquid crystal mode (VA-FFS) in thepresent invention at “off state” with no applied voltage.

FIG. 2 shows the structure of the liquid crystal mode (VA-FFS) in thepresent invention at “on state” with an applied voltage.

FIG. 3 shows the switching of molecules occurs only within very thinlayers of liquid crystals, which are generated as a result ofdisclinations.

FIG. 4 shows the switching of LC, which is much larger near thesubstrate surface.

FIG. 5 shows the elastic forces and the boundaries responsible for thevery fast relaxation.

FIG. 6 shows the structure of the Fringing-Field-Switching mode (FFS) atoff-state. (Prior Art)

FIG. 7 shows the structure and switching ofVertical-Alignment-In-Plane-Switching (VA-IPS). (Prior Art)

FIG. 8 shows the structure of the Optically Compensated Bend mode (OCB)(Prior Art)

FIG. 9 shows the use of symmetric upper and lower electrodeconfiguration in our present invention that can lower the operatingvoltage.

FIG. 10 shows the use of asymmetric upper and lower electrodeconfiguration in our present invention that can achieve maximum possibletransmission.

FIG. 11 shows a simulation of the optical response of the presentinvention with lower electrode only.

FIG. 12 shows a simulation of the optical response of the device in FIG.11 after using a higher birefringence of liquid crystal and result inhigher transmission.

FIG. 13 shows a simulation of the optical response of the presentinvention with asymmetric upper and lower electrode.

FIG. 14 shows the simulated optical response of the present inventionwith asymmetric upper and lower electrode and narrower electrode widthand gap of 2 micrometers (μm).

FIG. 15 shows the rise time of the simulated optical response in FIG.14.

FIG. 16 shows the fall time of the simulated optical response in FIG.14.

FIG. 17 shows the simulated optical response of the device in FIG. 14 at2 Volts (V).

FIG. 18 shows the rise and fall times of the device in FIG. 14 atdifferent applied voltages.

FIG. 19 shows the simulated optical response of the present inventionwith lower electrode only and wider electrode width and gap of 5 μm.

FIG. 20 shows the rise time of the simulated optical response in FIG.19.

FIG. 21 shows the fall time of the simulated optical response in FIG.19.

FIG. 22A shows the transmission profile of the present invention withlower electrode only.

FIG. 22B shows the director distribution of the present invention withlower electrode only.

FIG. 23A shows the transmission profile of the present invention withasymmetric upper and lower electrode.

FIG. 23B shows the director distribution of the present invention withasymmetric upper and lower electrode.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Before explaining the disclosed embodiment of the present invention indetail it is to be understood that the invention is not limited in itsapplication to the details of the particular arrangement shown since theinvention is capable of other embodiments. Also, the terminology usedherein is for the purpose of description and not of limitation.

Acronyms used throughout the description of the present invention aredefined as follows:

-   -   G—pixel electrode gap measured in micrometers (μm)    -   LC—liquid crystal    -   OCB—Optically Compensated Bend liquid crystal mode requires        continuous application of bias voltage.    -   PA—Parallel Alignment of liquid crystals    -   TN—Twisted Nematic liquid crystals    -   VA-FFS—Vertical Alignment Fringing Field Switching liquid        crystal mode of the present invention uses very low voltage,        e.g., <5V.    -   VA-IPS—Vertical Alignment In Plane Switching liquid crystal mode    -   W—pixel electrode width measured in micrometers (μm)

The operating principle of the liquid crystal mode in the presentinvention is based on the Fringing-Field Switching (FFS) ofVertically-Aligned (VA) liquid crystals; this novel mode is hereinafterdenoted as VA-FFS. The structure of this liquid crystal mode is shown inFIG. 1. Liquid crystal molecules 10 are sandwiched between a topsubstrate 22 and a bottom substrate 12. The alignment of the liquidcrystal molecules 10 is vertical at the “off state” where there is noapplied voltage. The transmission is thus zero when the device is placedbetween crossed polarizers since there is no birefringence experiencedby the incident light. In the bottom substrate 12, the pixel electrode14 next to the liquid crystal layer consists of discontinuous and narrowsegments. These pixel electrode segments within one pixel are allconnected to the same voltage source via a thin-film transistor. Thispixel electrode 14 is separated from the bottom common electrode 18(could be ˜0V) by a passivation layer 16. The passivation layer 16 isusually silicon dioxide or any other commonly known insulation materialand it is used as insulation between the pixel electrode 14 and thecommon electrode 18. The width of each pixel electrode segment will bedenoted by W and the width of the gap between adjacent segments will bedenoted by G as shown in FIG. 1. Discontinuous and narrow segments of apixel electrode for the present invention are in a range fromapproximately 1 micrometer (μm) to approximately 10 micrometers (μm);preferably between approximately 2 μm to approximately 7 μm. When thevoltage of the pixel electrode 14 is switched on, e.g. from 0V to 5V, anelectric field pattern 28 is generated as shown in FIG. 2. This electricfield switches the vertically aligned molecules and generates a brightstate between crossed polarizers. The switched molecules relax back tothe original state when the applied voltage is removed. It is found thatthe relaxation time of this liquid crystal mode becomes exceedinglyfast, e.g., in a range from 1 millisecond to 3 milliseconds (ms) when Wand G of the pixel electrode become very narrow, e.g. 3 μm or below.Although, in general, W and G can have different values, throughsimulations it has been found that highest light efficiency is usuallyobtained when W and G are equal. For example, when W=G=3 μm, both riseand fall (relaxation) times are often as short as 3 milliseconds (ms) orbelow. Moreover, these fast responses can occur at a relatively lowvoltage, e.g. 2-5 Volts (V), and in a thick cell (e.g. 5-5 μm). Theseunusual fast responses suggest that this novel liquid crystal mode canhave significant potential for low voltage, fast response, nematicliquid crystal modulators.

The mechanisms for the unusual fast response involve strong boundaryeffects provided by disclinations (K₁₁) and strong boundary effectsprovided by substrate surface (K₃₃).

As shown in FIG. 2, due to the interaction of LC molecules with thegenerated electric field, regular disclinations 25, also known as“unswitched molecules,” exist above the pixel electrode. Thesedisclinations 25 cause the switching of LC molecules 20 to be confinedwithin very thin layers or horizontal sections that are perpendicular tothe vertically aligned LC molecules. For example, when W=G=3 μm, LCmolecules are only allowed to switch within 1.5 μm layers of LC as shownin FIG. 3. The LC layers 30 are so thin that the majority of the LCmolecules are influenced and governed by the adjacent disclinations 25.The disclinations 25 act as strong boundaries which induce very highrestoring forces (due to elastic constant K₁₁) on the switched LCmolecules 20 after the removal of an applied voltage and result in veryfast relaxation. This is very similar to the mechanism for the fastresponse, which occurs in LC devices with very thin cell gap since amajority of the molecules in these devices are strongly controlled andinfluenced by the boundary (alignment) layers. This is justified by thefact that the relaxation time of the LC mode in this invention remainsvery fast even after the removal of a very small voltage, e.g. 2V.

Referring now to the strong boundary effects provided by a substratesurface (due to elastic constant K₃₃). In FIG. 3, substrate surface 12supports pixel electrode 14 and when W and G of the pixel electrodebecome very small, most of the electric field generated is concentratednear the electrode, i.e. the electric field is much stronger near thesurface of the substrate 12. Therefore, the extent of the LC switching(i.e. angle of rotation) is much larger near the substrate surface thanin the bulk as shown in the simulated director distribution in FIG. 4.The relaxation speed of these molecules is thus further enhanced by thestrong elastic force due to K₃₃ provided by the boundary layer(alignment layer) on the substrate surface. The relaxation process ofthis type of LC mode where the switching occurs mainly near boundaries,similar to the OCB liquid crystal mode, is in general much fastercompared with LC modes where the molecules in the bulk also switchsignificantly.

FIG. 5 summarizes the elastic forces and boundaries around the switchedmolecules responsible for this fast response mode. The switchedmolecules shown in FIG. 5 correspond to the active LC layers 30 shown inFIG. 3. K₁₁ and K₃₃ are elastic constants that correspond to differenttypes of elastic forces exerted on the active molecules. K₁₁ tends to bealong the longer, vertical axis of the molecule and K₃₃ tends to bealong the shorter, horizontal axis of the molecule. Splay and Bend arethe technical names used to distinguish the different types of elasticforces. Thus, Bend K₃₃ represents elastic forces in a horizontaldirection and Splay refers to the elastic forces in a verticaldirection. Compressed Splay occurs when the molecules are squeezedagainst each other and Stretched Splay occurs when the molecules arebeing pulled apart. In both cases, compressed and stretched splay, themovement creates an elastic force along the vertical length of themolecule.

Below are further embodiments that can enhance the efficiency orbrightness of a device using the present invention.

One embodiment uses symmetrical upper and lower electrodes as shown inFIG. 9. In a lower stacked arrangement, a first substrate 92 is adjacentto a common electrode 94 adjacent to a passivation layer 96 that isadjacent to a discontinuous pixel electrode 98. Opposite andsymmetrically aligned is an upper stacked arrangement having a secondsubstrate 192, adjacent to a second common electrode 194, adjacent to asecond passivation layer 196 attached to a second discontinuous pixelelectrode 198. This configuration can lower the required voltage toattain a certain transmission compared with the lower electrode onlyconfiguration shown in FIG. 1.

Another embodiment uses asymmetric upper and lower electrodes as shownin FIG. 10. In a lower stacked arrangement, a first substrate 102 isadjacent to a common electrode 104, adjacent to a passivation layer 106that is adjacent to a discontinuous pixel electrode 108. Opposite andasymmetrically aligned is an upper stacked arrangement having a secondsubstrate 112, adjacent to a second common electrode 114, adjacent to asecond passivation layer 116 attached to a second discontinuous pixelelectrode 118. This configuration allows the transmission to increasesignificantly since the switched LC molecules in the upper electrodecompensate for the unswitched LC molecules (disclinations) in the lowerelectrode, thus increases the maximum possible transmission.

Simulation results for each of the embodiments of the VA-FFS liquidcrystal mode of the present invention are shown in FIGS. 11 to 23.

FIG. 11 shows the simulation result of the optical response of a 5.5 μmthick VA-FFS (with lower electrode only) device to an applied voltage of5V. The liquid crystal has birefringence (Δn) of 0.2 whereas otherphysical properties are taken the same as LC ZLI-4535, the product codefor a liquid crystal that is commercially available from Merck, Inc.(K₁₁=9.3 pN, K₂₂=5.9 pN, K₃₃=11.8 pN and Δε=14.8). The device has W=G=3μm. The transmission of this cell is not so high, ˜8.5%, which is about8.5/35=˜24%. The transmission is divided by 35 since 35 corresponds to100% normalized transmission of the conventional twisted nematic (TN)cell. However, the response times are unusually fast. The rise time is<3 ms and the fall time is <1 ms. Moreover, this happens at a relativelylow voltage of 5V.

By using higher birefringence liquid crystal, one can increase thetransmission of the device in FIG. 11. For example, by using Δn of 0.4,the transmission is approximately doubled to 17.5%, which is 50% of TNas shown in FIG. 12.

By using asymmetric upper/lower electrode, the potential transmissioncan be maximized. For example, the transmission of a device withasymmetric upper and lower electrodes is ˜33.5/35%=˜96% at 6V with LCΔn=0.4 as shown in FIG. 13. Other LC physical parameters are K₁₁=12 pN,K₂₂=6 pN, K₃₃=16 pN and Δε=10. Cell gap of the device was 15 μm thick inorder to reduce the influence of the electric fields between top andbottom electrode.

By using W=G=2 μm, the response time can be reduced even further at theexpense of higher applied voltage. For example, the electro-opticresponse of a device using asymmetric upper and lower electrodes withW=G=2 μm is shown in FIG. 14. The rise and fall times are only ˜0.45 msand ˜0.55 ms as shown in FIGS. 15 and 16. The LC is ZLI4535 with Δn=0.4and transmission reaches maximum at almost 100% at the applied voltageof 8V. FIG. 17 shows the optical response of the device when it is underan applied voltage of 2V. As can be seen from the figure, this liquidcrystal mode offers unusual fast relaxation even at very small appliedvoltages. In fact, the relaxation time (fall time) becomes shorter atlowered applied voltage since the molecular perturbation becomes smallerat lower applied voltage. FIG. 18 shows the rise and fall times of thedevice at different applied voltages. As can be seen from the plot, bothrise and fall times are very fast <2 ms even at low applied voltages.The relaxation time becomes shorter as voltage is lowered due to lowermolecular perturbation whereas rise time increases as voltage is lowereddue to lower applied electric field; rise time is field-driven.

FIG. 19 shows the optical response of a device when the electrode widthW and gap G are=5 μm. In this example, only a lower electrode was used.FIGS. 20 and 21 show that the rise and fall times of the devices arestill very fast at ˜4 ms and ˜3.5 ms respectively. The transmission of a10 μm thick device is ˜20/35=˜57% at an applied voltage 6V. Δn of the LCused is 0.2 and other physical parameters of LC are taken as those ofZLI4535. Higher transmission is possible by including an upperelectrode. These results can be important for manufacturers where thefabrication capability of narrow pixel electrode is more limited.

The optical response of the device for intensity modulation has beendemonstrated. However, phase modulation is often required for opticalcommunication applications. The fact that the amount of induced phaseshift for phase modulation is proportional to the amount of inducedretardation for the intensity modulation suggests that we can deduce thephase modulation capability of the device by analyzing the intensitymodulation behavior. In general, intensity modulation operates when thedevice is placed between crossed polarizers and that the incident beamis polarized at 45° relative to the plane of optic axis rotation.Incident light experiences both ordinary and extraordinary indices n_(o)and n_(e(eff)). Upon an applied voltage, transmission changes from 0 to100% when a π optical retardation is induced. This π optical retardationhowever becomes a π pure phase-shift when the device operates in thephase modulation mode, which occurs when the incident beam is polarizedalong the plane of optic axis rotation, instead of 45° as for intensitymodulation. Thus, the incident beam experiences n_(e(eff)) only.Therefore, a full intensity transmission in intensity modulation alsocorresponds to a π phase shift in phase modulation.

In general, if the transmission profile is examined across a pixel inthe device of the present invention with lower electrode only, it has arather non-uniform output profile as shown in FIG. 22A. This is due tothe non-uniform switching of LCs caused by the disclinations and thegenerated electric field pattern as shown in simulated directordistribution in FIG. 22B. This non-uniformity is acceptable forapplications such as displays where the intensity of a pixel perceivedby the human eyes is spatially averaged. However, for phase modulation,this non-uniformity corresponds to non-uniform phase shift across thepixel. Better uniformity is desired in order to maximize the phasemodulation efficiency. By using asymmetric upper and lower electrodes,the transmission profile becomes much more uniform as shown in FIG. 23A.This happens as a result of the compensation offered by the upperelectrode. Simulated director distribution of a LC device withasymmetric upper and lower electrodes is shown in FIG. 23B. Furtherimprovement of the uniformity may be obtained by careful design andoptimization of the electrode.

The transmission shown in FIG. 23A is ˜100%, since 0.35 transmission onthe figure corresponds to 100% normalized transmission, whichcorresponds to a π pure phase-shift or phase modulation. The pixelelectrode width W and gap G are both 2 μm. The applied voltage is 8Vwith Δn of LC=0.2 at wavelength of 550 nm. By using Δn=0.4, a 2 π phaseshift may be obtained. To obtain a 2π phase shift at 1550 nm infraredregion, further improvements on the device design or LC birefringencemay be required.

Due to the mirror symmetry of the molecular switching which results inmulti-domain formation, this liquid crystal mode has inherentwide-viewing-angle property, which is a very desirable property fordisplay applications.

Other potential applications for the present invention include, but arenot limited to, optical-phased-arrays for beam-steering, high-speedcolor sequential displays, TV displays with fast response andwide-viewing angle. Those skilled in the art will perceive additionalapplications when the advantages of the present invention are discussedin view of current technology.

The present invention provides a faster response that theFringing-Field-Switching liquid crystal mode and theVertical-Alignment-In-Plane-Switching mode. The present invention ismore stable and does not require bias voltage, as does the OpticalCompensated Bend liquid crystal mode. With regard to conventional liquidcrystal cells which can have Vertical Alignment (VA), Parallel Alignment(PA), or Twisted Nematic (TN) cells that require a thin cell gapstructure; the present invention does not require a thin cell gap.

Thus, the present invention provides a unique structure, the VerticallyAligned-Fringing Field Switching (VA-FFS) liquid crystal mode capable ofgenerating very fast optical modulation without the use of a very thincell gap. Fast relaxation occurs even at very low applied voltages andthe operation is very stable. The end result is a fast response liquidcrystal mode to meet the demand and use in advanced display systems andoptical communication systems.

While the invention has been described, disclosed, illustrated and shownin various terms of certain embodiments or modifications which it haspresumed in practice, the scope of the invention is not intended to be,nor should it be deemed to be, limited thereby and such othermodifications or embodiments as may be suggested by the teachings hereinare particularly reserved especially as they fall within the breadth andscope of the claims here appended.

1. A method of producing a stable, fast-response optical modulator withvertically aligned (VA) fringing field switching (FFS) liquid crystals,comprising the steps of: a) forming a top substrate and a bottomsubstrate capable of supporting a top and bottom common electrode,respectively, connected to a voltage source, b) placing a nematic liquidcrystal layer between the top and bottom substrate of (a) so that themolecules of said crystal are vertically aligned when there is novoltage applied, c) including top and bottom pixel electrodes on the topand bottom substrates, respectively, next to the liquid crystal layer,said pixel electrodes having discontinuous and narrow segments, whereinthe top pixel electrodes are parallel to the bottom pixel electrodes;and d) connecting the top and bottom pixel electrodes of c) to a voltagesource; and e) providing insulation between the top and bottom pixelelectrodes and the top and bottom common electrode with a passivationlayer; whereby intensity and phase modulation for displays and opticalcommunication are accomplished.
 2. The method of claim 1, wherein thepixel electrodes are in segments having a width (W) and a space betweensegments forming a gap (G).
 3. The method of claim 2, wherein W and Ghave the same value.
 4. The method of claim 2, wherein W and G are belowapproximately 7 micrometers (μm).
 5. An optical response device forproducing stable, fast-response optical modulation comprising: a topsubstrate and a bottom substrate having a top common electrode and abottom common electrode connected to a voltage source and adjacent tothe top substrate and bottom substrates, respectively, nematic,vertically aligned liquid crystal (LC) molecules, self-imposed strongboundary layers provided by unswitched LC molecules, fringing fieldswitching in the operational mode, a top pixel electrode and a bottompixel electrode having a voltage connection, wherein the bottom and topelectrodes are discontinuous and are aligned symmetrically parallel toeach other, and a passivation layer.
 6. The optical device of claim 5,wherein the self-imposed strong boundary layers comprise unswitched LCmolecules being held in a stationary position by adjacent fringing fieldswitching molecules interacting with a generated electric field abovethe pixel electrode.
 7. The optical device of claim 6, wherein thefringing field switching occurs in very thin horizontal sections thatare perpendicular to the vertical alignment of the LC molecules.
 8. Theoptical device of claim 7, wherein the fringing field switching occursin horizontal sections of less than approximately 3.5 μm in length. 9.The optical device of claim 5, wherein the pixel electrode consists ofdiscontinuous and narrow segments.
 10. The optical device of claim 9,wherein the discontinuous and narrow segments include: a narrow width(W) of less than approximately 7 μm; and a narrow gap (G) of less thanapproximately 7 μm.
 11. The optical device of claim 5, wherein the pixelelectrode has a thin-film transistor for a voltage source.
 12. Theoptical device of claim 5, wherein the bottom and top pixel electrodesare aligned symmetrically.
 13. The optical device of claim 5, whereinthe passivation layer separates the top and bottom pixel electrodesegments from the top and bottom common electrodes adjacent to the topand bottom substrates.
 14. The optical device of claim 13, wherein thepassivation layer is an electrical insulating material.